Composite Amplifier with Extremely High CMRR

Building high precision instruments needs almost ideal operational amplifiers. Effects of offset, common mode rejection ratio (CMRR) and other imperfections have to be reduced as much as possible. One way is to apply precision operational amplifiers but their parameters are limited and their price is high. Another approach is to use composite amplifiers proposed in this text. Instead of a single operational amplifier, composite amplifiers are built from two or more operational amplifiers with significant improvements in resulting parameters. The research is started with theoretical analysis. Benefits of the proposed circuits are shown by simulations on the simulation models and measurements on the real model. The theory and practice introduced below could be well included in undergraduate course in analog electronics